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How To Treat Osteosarcoma When Surgery Is Refused

Katherine Skorupski explains how a pet owner can help treat osteosarcoma when surgery is not an option.

A dog with distal tibial osteosarcoma undergoes palliative radiation therapy using a linear accelerator.

Photo Courtesy of Dr. Michael Keat, UC Davis

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Osteosarcoma (OSA) is a common and devastating cancer that plagues many of our canine patients. Standard-of-care therapy continues to include the recommendation for surgical removal of the primary tumor through amputation or through limb-sparing surgery followed by chemotherapy. 

However, some patients may not be good candidates for amputation or their owners may prefer to pursue non-surgical alternatives. Recent years have brought new radiotherapy techniques as well as new options for pain control.

External beam radiation therapy has been studied as a palliative treatment for OSA for many years and is used strictly to impart local pain control. Total radiation doses of 24 to 36 Gy are administered to the tumor site over three to four weekly fractions. Significant pain relief is expected in 74 to 92 percent of dogs for a median of two to three months, although most dogs will still require some pain medications. 

Skin reactions are mild with this palliative dosing scheme and generally do not affect quality of life. Local tumor control is not expected with this treatment modality and, occasionally, pathologic fracture may occur at the tumor site. This treatment option is available at many universities and specialty practices across the country.

A Promising Modality

Another type of radiation therapy termed stereotactic radiosurgery, or SRS, is a new non-surgical treatment option available to dogs with OSA. 

First reported in dogs in 2004 by the University of Florida, this modality administers a very high dose of radiation to the tumor while sparing most of the normal surrounding tissues. SRS entails either a single high dose or a few slightly smaller doses with the help of highly advanced treatment planning equipment. 

SRS can result in necrosis of a high percentage of tumor cells, a result not possible with traditional palliative radiation therapy. While further study is necessary, SRS may be able to provide long-term pain control as well as tumor control without the need for surgery.

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Pathologic fracture is still a problem with this type of therapy and may be delayed by four to six months after treatment. 

This treatment modality is available at the University of Florida, Colorado State University and the Animal Specialty Center in Yonkers, N.Y.

Samarium 153 lexidronam is a radioisotope bound to a salt that can be administered intravenously and concentrates in areas of increased osteoblastic activity. Treatment resulted in pain reduction in 63 percent of dogs with bone tumors in one study, but did not prevent local tumor progression or extend survival time. It seems to be most effective in dogs with small tumors. 

Three to four days of hospitalization is required after treatment while radioactivity within the patient resolves. Neutropenia or thrombocytopenia occurred in the majority of patients treated. Treatment with Samarium 153 lexidronam can be repeated safely if necessary. This therapy is available at the University of Missouri, Colorado State University and the Veterinary Specialty Center in Buffalo Grove, Ill.

Osteoclast Inhibitors

A lot of interest has been shown recently in the use of bisphosphonates in dogs with OSA. This class of drugs, which includes pamidronate and zoledronate, act as osteoclast inhibitors and are used extensively in people with metastatic breast or prostate cancer to bone. 

Bisphosphonates appear to also have some direct anti-neoplastic effects. In a recent study, 30 percent of dogs with OSA treated with pamidronate achieved durable pain control for a median of 7.7 months. Pamidronate is administered as a two-hour intravenous infusion with saline every four weeks and has an extremely low risk of side effects. Bisphosphonates may be used in combination with radiation therapy to increase the chances of achieving adequate pain control.

Pain Control

The importance of vigilant medical pain control as a viable short-term treatment option should not be underestimated. Non-steroidal anti-inflammatory drugs (NSAIDs) continue to be the cornerstone of treatment for patients with OSA who do not undergo surgery, and more drug choices are available now than ever. 

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NSAID therapy alone, however, is rarely adequate to control pain and improve mobility in dogs with OSA. The addition of Tramadol is usually necessary even in early cases and, because it has a wide dose range, it can be titrated to reach the ideal effect in each patient. 

At high doses, this drug may cause sedation, agitation or gastrointestinal side effects. Amantadine or gabapentin may be added to the combination of an NSAID and Tramadol in patients with acute pain, and both are generally well tolerated.

Other Options

Should non-controlled drugs fail to achieve the desired degree of pain control, codeine, extended-release morphine or other oral opiates may be prescribed. Sedation and constipation are common side effects of these drugs, however, and the patient’s quality of life should be seriously considered before long-term use of these drugs is recommended.

At the University of California, Davis, veterinary medical teaching hospital, we always encourage routine recheck examinations even for patients with OSA receiving only pain-control medications. This allows us to reassess pain levels and modify the treatment plan as the tumor progresses locally. 

In summary, many options other than surgery exist for veterinarians who treat dogs with OSA. Most of these treatments focus on pain control and quality of life, important considerations for any cancer patient. 

Research in this field is ongoing. Additional radiotherapy and medical options as well as other novel therapies are likely to become available within the next several years.

Dr. Skorupski, Dipl. ACVIM (oncology), is assistant professor of clinical medical oncology at the University of California, Davis.

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15 thoughts on “How To Treat Osteosarcoma When Surgery Is Refused

  1. Hi Dr.Storupski,
    We have a 7-8 yr.old Rott/Mastiff mix that was diagnosed this Monday with osteosarcoma of his upper humorous…he started limping last Wed. We go to Pets Friend in Sunnyvale. Do you have any new treatments?
    Amputation is not an option…
    Thank you,
    Donna Borges

    1. Hi doctor
      My five year dog had swelling in right shoulder since one month.he was taken x ray and done FNAC.vet doctor diagnosed cancer of humerus bone and not indicate for surgery.so could you suggest for further management including pain ?I hope yoursuggest may Change quality of life

  2. We have a 10 year old golden retriever that was diagnosed with osteosarcoma early in March of this year.
    Amputation was not an option either .
    She has been doing really well and is still enjoying a good quality of life although she does hobble and offload weight-bearing on her one leg.
    We have tried the following and it seems to be helping :
    –pamidronate infusion for two hours once a month.
    — two doses daily of Metacam.
    — cannabis oil twice a day (CBD:THC 1:1)
    — we also did some acupuncture treatments (4-5 weekly)from a holistic vet at the beginning of the diagnosis but I question the efficacy of that
    — she has been on a raw food diet all along so that obviously didn’t prevent osteosarcoma .

    1. We have a 9 1/2 Pitt/lab mix recently diagnosed with bone cancer in his back right leg. He also has a pathological fracture. We can’t do the chemo (cost). We are currently treating the pain with tramadol. It is breaking our hearts as we love him so very much. Just amputating his leg without chemo would only give him 3-4 mos. Presently he is happy and eating well. He limps. We know we don’t have much time. Even if we could afford amputation with chemo is it worth putting them through all this?

      1. I’m not a vet but I would say yes. Hind legs are much easier on the dog than front amps, and chemo does not effect dogs the way it does humans. If you go to “Osteosarcoma in Dogs” or “Bone Cancer in Dogs” chat sites, you’ll get a wealth of information and experiences from people on the same road.

      2. My 13 year old lab was just diagnosed and I’m not doing amputation or chemo she’s happy eating and still hobbling and wants to play ball so I’m going to manage her pain somehow although she doesn’t seem to be in pain…

      3. My dog was diagnosed with Soft Tissue Osteoblastic Osteosarcoma back in August. Because the biopsy failed to heal (the tumor grew straight through the surgical incision within a few days), we were forced to amputate his right, front leg immediately or put him to sleep. After multiple surgeries (the incision became infected and he had to have four follow up surgeries to get it to heal properly), he was on several pain medications (gabapentin, tramadol, and carprofen). He didn’t tolerate them well (though gabapentin seemed to be the best for him), but luckily didn’t need them after his incision healed. It took him only a week to get used to having three legs and he lived a very normal, fulfilling life for four more months. We had to accommodate him in some ways: higher food bowls to help him keep his balance, socks with rubber soles on the hardwood floors, and although he could navigate steps and jump up and down off beds and couches, OSA diagnosed dogs are prone to fractures so we would carry him up and down steps to go outside or go to bed in order to mitigate the chances of that happening. However, he only weighs 20lbs; so for larger breeds, I would look into assistance lifts or leg/joint braces. About two weeks ago, I noticed a small growth (the size of a marble) adjacent to his incision scar. He started to slow down. He was pickier about eating, but still eating quite a lot. He was having a harder time balancing (he appeared to lose strength in his back legs), defecating, and sleeping. I could tell he was in pain (his giveaway is fast, shallow panting and shifting a great deal during sleep). I decided to forego traditional pain meds as they seemed to cause him more discomfort (heavy, labored breathing, excessive drooling and thirst, increased heart rate, and constipation). Instead, I purchased 750mg CBD oil and give him a half dropper (about 15 drops) every 4 to 5 hours. The minute it kicks in, his breathing becomes normal and he is more willing to get up and walk around. His appetite is great and he is still the sweetest dog I’ve ever been around. It doesn’t help him go to the bathroom more easily, so occasionally if needed, I give him 5mg Dulcolax to help him pass a BM more easily — Only if I notice he hasn’t passed a large BM in over a day or two. With the amount of food he eats and his usual habits, he normally goes twice a day. In addition, I supplement him with Glucosamine chews and a diet of organic wet food and homemade meals. Today, the growth is about the size of a baseball. Because of it’s location and size, it is cutting off blood supply to his face causing his eyes to become bloodshot and milky and his tongue and gums to become slightly purple. We have scheduled an in-home euthanasia for Monday morning.

        You asked if it was worth it. I would say it depends entirely on you. I have been blessed with four more wonderful months of memories with a dog that has been by my side for half of my lifetime. For me, it was worth it. I was told by a few people close to me that it wasn’t– that I was going to “extreme measures” and delaying the inevitable. These same people are going to great lengths to keep their aging parents alive – there is no difference in my mind. Just be cognizant of your dog’s quality of life as well as your peace of mind.

        1. I am so sorry to hear that your fur baby has reached his limit here on earth. I completely understand what you’re going through. I have a 10 y/o English Mastiff going through this. He was diagnosed approximately a month ago and it has been one of the hardest things to go through. As of last night, he is not putting much weight on the leg and due to his weight (approximately 150 lbs) and age, he does not get around too well on the three legs. I just hung up with the veterinarian and they are going to up his Tramadol and Carprofen, but I know I too am just prolonging the inevitable, but I will take all the time in the world that I can get with him. It is heart breaking, as you know. My thoughts and prayers are with you and your family.

          1. I’m so sorry to hear about your pup. It’s been one day since my little man went over the rainbow bridge and I’m finding it very difficult to do much of anything. I still don’t regret getting as much time as I could with him. As long as you feel like you’re managing his pain well, take as much time as you possibly can. My thoughts and prayers are with you.

  3. My dog was diagnosed 2 months ago. At the time I didn’t have the money for amputation. Now I have been able to save some. Would the amputation provide a better quality of life at this time given how long ago he was diagnosed ??

    1. I think that would depend on whether or not the cancer has metastasized. Amputation won’t slow the progress of the disease if that’s the case. The main reason I had to amputate is because his biopsy wound wouldn’t heal. The remaining tumor grew through the surgical incision in a matter of days and was causing him a great deal of pain, not to mention blood loss, so it was either amputate or euthanize. Mind you, this was one week after his diagnosis. Up until then, I had a perfectly healthy, happy dog that still acted like a puppy. So I couldn’t wrap my head around him being sick. There is no right answer, only what’s best for you and your baby.

      I’m not sure what kind of dog you have or where you live, but I would encourage you to look into the clinical trials currently taking place for Osteosarcoma in Dogs, as well as several other cancer types. There are about 13 at present time located all over the US. One of the most promising is for a Listeria vaccine that kills cancer cells. It has already been approved for conditional use by the FDA and given to 20 clinics around the US to use on patients. If your dog is a candidate, they will pay for the amputation, chemo/radiation, and the 4 vaccinations. If he isn’t a candidate, the vaccinations are still available through the selected vet, but the out of pocket cost for the 4 vaccinations and bloodwork is around $4k. Chewy wasn’t a candidate and I had already sunk about $3k into his treatment, so I wasn’t able to afford it.

  4. what type of canabis oil?My dog has bone cancer and we want him to be comfortable – where and what brand of cannabis oil is best and where to buy? I live in Chicago

    1. I was using Hempworx 750mg natural flavored CBD oil. It’s the cleanest and purest I’ve been able to find. Dogs are more sensitive to THC than humans, so get as low THC content as possible or none at all. I was giving my 20lb Brussels about 15 drops 2 to 3 times a day. That is a very high dose, so I would recommend titrating up to that if needed. I think the recommend dosing is 1-5mg per kg of weight every 6 hours. CBD is sold in total mg meaning my 750mg bottle wasn’t 750mg per dose, but 750mg in the entire bottle which is 1oz or 30ml. There are usually 15 to 20 drops per ml (generally one full dropper is equal to 1 ml) depending on the viscosity of the liquid. So 30ml x 15 drops = 450 drops. So 750mg ÷ 450 drops = 1.6mg of CBD per drop. Now this is only accurate if the product you are using doesn’t contain any fillers, so be aware of that. So Chewy’s dose should have been 9kg (20lbs ÷ 2.2) × 5mg (highest recommended dose) = 45mg of CBD every 6 (to 8 hours). I went with the highest maximum dose and earliest dosing interval here to show a maximum, but owners should be cognizant of how their dog reacts to the CBD and always start with the lowest dose and work your way up. So 45mg ÷ 1.6mg = 28 drops of CBD. You can use this same equation to figure out dosing for different weights or different diseases and ailments.

  5. Hi Rebecca, our THREE YEAR OLD pure breed malamute started limping just before Christmas and just got diagnosed with primary osteosarcoma. It was “incredibly small” on the xray. It has been less than a month and today he is barely able to stand up and is crying profusely (it actually is harder for him to lay down) Because of the holidays, determining next steps has been a huge bottleneck. We have been given gama and tram to administer.. but it doesn’t seem to calm him. We gave him two tram at 7:30 am and at 9am its as if he didn’t even have it. He is so young and the change has been so rapid – we were planning on an the next available amputation appointment on Wed but we are having troubles just getting through the night. He is actually howling. My questions: 1.) do you have an inexpensive online resource to get the Hempworx? 2.) have you heard of treating this with mushrooms? 3.) we were planning on getting an xray of his lungs but I’m hearing it’s pointless because micro evidence never shows up on xray. How are the vets able to rule out other locations in the body that might be causing additional pain? We just cant tell if we are ‘doubling’ the trauma if we were to go the amputation route – plus cash is very tight.. so hard to navigate. Any additional thoughts would be helpful.

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